---
title: "Policy Preferences, Ideology, and Support for Donald Trump"
author: |
  | Doug Ahler, Graduate Student, UC Berkeley, dahler@berkeley.edu
  | David Broockman, Assistant Professor, Stanford GSB, dbroockman@stanford.edu
output: pdf_document
---

This note provides the technical detail for our Monkey Cage post about Donald Trump on December 16, 2015. The data and replication code can be downloaded at [https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/ISUBXL](https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/ISUBXL).

The working paper that makes the general argument is available [here](https://people.stanford.edu/dbroock/sites/default/files/ahler_broockman_ideological_innocence.pdf).

```{r, include=FALSE}
setwd('~/Google Drive/Broockman-Ahler/Oct 2015 Primaries Survey _ Monkey Cage Post')

# Load data.
library(foreign)
data <- read.dta('ideology_primaries_issues.dta', convert.underscore = TRUE)
```

# Sample

`r nrow(data)` respondents completed the survey. The survey was open October 13 - October 15, 2015. Of the `r nrow(data[data$pid>0,])` Republicans in the sample, `r nrow(data[data$pid>0 & data$trump==1,])` support Trump. `r nrow(data[data$pid<=0 & data$trump == 1,])` non-Republicans also support Trump.

# Results

```{r, warning=FALSE}
# Generate party variable.
data$republican <- data$pid > 0
data$party[data$pid > 0] <- "Republicans"
data$party[data$pid <= 0] <- "Democrats"
data$party[data$pid == 0] <- "Independents"
data$party <- as.factor(data$party)

# Generate "moderation" variable.
data$ideological.moderation <- -1 * abs(data$ideal.point.general)

# Regressions that don't rely on subsample asked immigration question.
  # "Moderation"" predicts support for Trump.
  summary(lm(trump ~ republican + ideological.moderation, data))
  summary(lm(trump ~ party + ideological.moderation, data))

# Plots.
library(ggplot2)
library(scales)

make.plots <- function(x.var, x.name){
  data.tmp <- subset(data, !is.na(x.var) & !is.na(pid))
  g <- ggplot(data = data.tmp, aes(y = trump)) +
    geom_smooth(aes_string(x = x.var), se = FALSE, span = 2) +
    facet_wrap(~ party) + 
    xlab(x.name) + ylab("Percentage Supporting Trump") +
    theme_bw() +
    ggtitle(paste0(x.name, " and Trump Support")) +
    scale_x_continuous(breaks=NULL) + scale_y_continuous(labels=percent)
  ggsave(paste0(x.var,".png"), g)
  
  g.reps <- ggplot(data = subset(data.tmp, pid > 0), aes(y = trump)) +
    geom_smooth(aes_string(x = x.var), se = FALSE, span = 2) +
    xlab(x.name) + ylab("Percentage Supporting Trump") +
    theme_bw() +
    ggtitle(paste0(x.name, " and Trump Support\nAmong Republican Voters")) +
    scale_x_continuous(breaks=NULL) + scale_y_continuous(labels=percent)
  ggsave(paste0(x.var,".repubs.png"), g.reps)
  
  return(list(g, g.reps))
}

make.plots("ideal.point.general", "Left-Right Ideology")
make.plots("ideological.moderation", "Ideological Moderation")
make.plots("ideal.point.immigration", "Conservatism on Immigration")
make.plots("eq.taxes", "Conservatism on Taxes")


# Subset sample to those asked immigration questions; we asked these to a random 1/3.
data <- subset(data, !is.na(ideal.point.immigration))

# Regressions.
# Ideology doesn't predict support for Trump, but immigration and taxes do.
summary(lm(trump ~ republican + ideal.point.general + ideal.point.immigration, data))
summary(lm(trump ~ republican + ideal.point.general + ideal.point.immigration + eq.taxes, data))
summary(lm(trump ~ ideal.point.general + ideal.point.immigration + eq.taxes, data, republican == TRUE))
# Ideological moderation is negatively correlated with Trump support within parties.
summary(lm(trump ~ republican + ideological.moderation, data))
summary(lm(trump ~ party + ideological.moderation, data))
```

# Items

## Party ID

Party ID was assessed using the typical ANES branching question.

## Support for Trump

Support for Trump was assessed two items.

For the first item, we first asked respondents "If there were a Presidential Primary election in your state, would you vote in the Democratic primary, the Republican primary, or would you wait to vote in the general election in November 2016?" If respondents picked "Republican," we then gave them a list of candidates, including Trump, with the prompt "Below is a list of people who may be running in the 2016 Republican presidential primaries. Please indicate which of those candidates you would be most likely to support in the upcoming primary elections."

We also asked an open-ended item: "If the 2016 Presidential election were held tomorrow, would you vote for..." followed by Clinton, Sanders, Trump, Bush, 'a different Democrat', and 'a different Republican' as choices.

We code someone as a Trump supporter if they supported Trump on either item.

## Scales

Ideal points were computed in STATA 14 using the "irt 2pl" command from the items listed below.

### General Ideology Scale Items

Respondents were asked whether they agree or disagree with the items below, which were presented in a randomized order.

* Same-sex couples should be allowed to marry.
* Legalize the purchase and possession of small amounts of marijuana.
* The government should not provide any funding to the arts.
* The U.S. government should approve the Keystone XL pipeline that would carry oil from Canada to Texas.
* The minimum wage employers must pay their workers should be increased.
* Regulate greenhouse gas emissions by instituting a carbon tax or cap and trade system.
* Require minors to obtain parental consent to receive an abortion.
* The government should provide parents with vouchers to send their children to any school they choose, be it private, public, or religious.
* The US should contribute more funding and troops to UN peacekeeping missions.
* Give preference to racial minorities in employment and college admissions in order to correct for past discrimination.
* I support free trade and oppose special taxes on the import of non-American-made goods.
* There should be strong restrictions on the purchase and possession of guns.
* The US should immediately act to destroy Iran’s nuclear weapons development facilities.
* The federal government should subsidize student loans for low income students.
* Increase taxes for those making over $250,000 per year.

### Immigration Preferences Scale Items

Respondents were asked whether they agree or disagree with the items below, which were presented in a randomized order.

* The United States should have open borders and allow further immigration on an unlimited basis. (1)
Legal immigration to the United States should greatly increase among all immigrant groups, regardless of their skills. All undocumented immigrants living in the United States should be given amnesty and put on the path to citizenship.
* A path to citizenship should be established for all undocumented immigrants living in the United States who lack criminal records, pay back taxes, and speak English.
* A path to citizenship should be established for undocumented immigrants brought to the United States as children who lack criminal records, pay back taxes, and attend college and/or serve in the military.
* Immigration of highly skilled individuals should increase, and immigration among those without such skills should be more closely controlled and limited in time and magnitude, e.g., through a guest worker program.
* On immigration, the government should primarily focus on securing the border with increased physical barriers to stem the flow of undocumented immigrants.
* Only a small number of highly skilled immigrants should be allowed into the United States until the border is fully secured, and all illegal immigrants currently in the US should be deported.
* Further immigration to the United States should be banned until the border is fully secured, and all illegal immigrants currently in the US should be deported immediately.
* The tradition of birthright citizenship, by which children born in the US to non-citizen parents automatically receive U.S. citizenship, should be ended.
* The tradition of birthright citizenship, by which children born in the U.S. to non-citizen parents automatically receive U.S. citizenship, should be ended AND people who have previously received birthright citizenship should have it revoked and be deported.

## Conservatism on Taxes Item

*Which statement comes closest to describing your views on federal taxes?*

1. Establish a maximum annual income, with all income over $1,000,000 per year taxed at a rate of 100%. Decrease federal taxes on the poor and provide more services benefitting the middle class and poor.
2. Increase federal income taxes on those making over $250,000 per year to pre-1990s levels (over 5% above current rates). Use the savings to significantly lower taxes and provide more services to those making less and to invest in infrastructure projects.
3. Increase federal income taxes on those making over $250,000 per year to 1990s rates (~5% above current rates). Use the savings to lower taxes and provide more services to those making less while also paying down the national debt.
4. Maintain current levels of federal spending and federal income taxes on the rich, middle class, and poor.
5. Decrease all individuals' income tax rates, especially high earners who pay the most in taxes now, accomplished by decreasing government services.
6. Move to a completely flat income tax system where all individuals pay the same percentage of their income in taxes, accomplished by decreasing government services.
7. Move to a flat consumption tax where all individuals pay the same percentage of their purchases in taxes, banning the income tax, even if this means the poor pay more in taxes than the rich. Significantly decrease government services in the process.